1151
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Jang S, Imlay JA. Hydrogen peroxide inactivates the Escherichia coli Isc iron-sulphur assembly system, and OxyR induces the Suf system to compensate. Mol Microbiol 2010; 78:1448-67. [PMID: 21143317 DOI: 10.1111/j.1365-2958.2010.07418.x] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Environmental H(2) O(2) creates several injuries in Escherichia coli, including the oxidative conversion of dehydratase [4Fe-4S] clusters to an inactive [3Fe-4S] form. To protect itself, H(2) O(2) -stressed E. coli activates the OxyR regulon. This regulon includes the suf operon, which encodes an alternative to the housekeeping Isc iron-sulphur cluster assembly system. Previously studied [3Fe-4S] clusters are repaired by an Isc/Suf-independent pathway, so the rationale for Suf induction was not obvious. Using strains that cannot scavenge H(2) O(2) , we imposed chronic low-grade stress and found that suf mutants could not maintain the activity of isopropylmalate isomerase, a key iron-sulphur dehydratase. Experiments showed that its damaged cluster was degraded in vivo beyond the [3Fe-4S] state, presumably to an apoprotein form, and thus required a de novo assembly system for reactivation. Surprisingly, submicromolar H(2) O(2) poisoned the Isc machinery, thereby creating a requirement for Suf both to repair the isomerase and to activate nascent Fe-S enzymes in general. The IscS and IscA components of the Isc system are H(2) O(2) -resistant, suggesting that oxidants disrupt Isc by oxidizing clusters as they are assembled on or transferred from the IscU scaffold. Consistent with these results, organisms that are routinely exposed to oxidants rely upon Suf rather than Isc for cluster assembly.
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Affiliation(s)
- Soojin Jang
- Department of Microbiology, University of Illinois, Urbana, IL 61801, USA
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1152
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Gonzalez A, Vera J, Castro J, Dennett G, Mellado M, Morales B, Correa JA, Moenne A. Co-occurring increases of calcium and organellar reactive oxygen species determine differential activation of antioxidant and defense enzymes in Ulva compressa (Chlorophyta) exposed to copper excess. PLANT, CELL & ENVIRONMENT 2010; 33:1627-40. [PMID: 20444222 DOI: 10.1111/j.1365-3040.2010.02169.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In order to analyse copper-induced calcium release and (reactive oxygen species) ROS accumulation and their role in antioxidant and defense enzymes activation, the marine alga Ulva compressa was exposed to 10 µM copper for 7 d. The level of calcium, extracellular hydrogen peroxide (eHP), intracellular hydrogen peroxide (iHP) and superoxide anions (SA) as well as the activities of ascorbate peroxidase (AP), glutathione reductase (GR), glutathione-S-transferase (GST), phenylalanine ammonia lyase (PAL) and lipoxygenase (LOX) were determined. Calcium release showed a triphasic pattern with peaks at 2, 3 and 12 h. The second peak was coincident with increases in eHP and iHP and the third peak with the second increase of iHP. A delayed wave of SA occurred after day 3 and was not accompanied by calcium release. The accumulation of iHP and SA was mainly inhibited by organellar electron transport chains inhibitors (OETCI), whereas calcium release was inhibited by ryanodine. AP activation ceased almost completely after the use of OETCI. On the other hand, GR and GST activities were partially inhibited, whereas defense enzymes were not inhibited. In contrast, PAL and LOX were inhibited by ryanodine, whereas AP was not inhibited. Thus, copper stress induces calcium release and organellar ROS accumulation that determine the differential activation of antioxidant and defense enzymes.
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Affiliation(s)
- Alberto Gonzalez
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
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1153
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Fischer BB, Rüfenacht K, Dannenhauer K, Wiesendanger M, Eggen RIL. Multiple stressor effects of high light irradiance and photosynthetic herbicides on growth and survival of the green alga Chlamydomonas reinhardtii. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2010; 29:2211-2219. [PMID: 20872684 DOI: 10.1002/etc.264] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Exposure of the green alga Chlamydomonas reinhardtii Dangeard to a combination of environmental stress by high light irradiance and chemical stress by each of the three herbicides paraquat, atrazine, and norflurazon resulted in diverse multiple stressor effects on growth and survival of the cells. Under low light conditions, growth analyzed by cell numbers was generally more sensitive to herbicide treatment than optical density-based growth rates or colony-forming unit endpoints, which both also analyzed the viability of the cells. However, growth analyzed by optical density and colony-forming units in herbicide-treated cultures was affected much more strongly by high light irradiance, as shown by reduced 50% effective concentrations, indicating extensive multiple stressor effects of the combined treatment on the viability of the cells. None of the currently used concepts for mixture toxicity (concentration addition, independent action, or effect summation) could accurately describe the effects measured by the two stressors in combination. Both synergistic and antagonistic interactions seem to occur depending on the light conditions and the parameter analyzed. The strong stimulation of toxicity by the combined stresses can be explained by the similar mode of toxic action of the treatments, all increasing the production of reactive oxygen species. Antagonistic effects, conversely, are probably attributable to the various protection mechanisms of photosynthetic organisms to increased light irradiance, which help the cells acclimate to specific light conditions and defend against the deleterious effects of excess light. These protection mechanisms can affect growth and viability under increased light conditions and also might influence the toxicity of the photosynthetic herbicides.
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Affiliation(s)
- Beat B Fischer
- Eawag, Department of Environmental Toxicology, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, CH-8600 Duebendorf, Switzerland.
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1154
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Zechmann B, Müller M. Subcellular compartmentation of glutathione in dicotyledonous plants. PROTOPLASMA 2010; 246:15-24. [PMID: 20186447 PMCID: PMC2947009 DOI: 10.1007/s00709-010-0111-2] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Accepted: 01/15/2010] [Indexed: 05/18/2023]
Abstract
This study describes the subcellular distribution of glutathione in roots and leaves of different plant species (Arabidopsis, Cucurbita, and Nicotiana). Glutathione is an important antioxidant and redox buffer which is involved in many metabolic processes including plant defense. Thus information on the subcellular distribution in these model plants especially during stress situations provides a deeper insight into compartment specific defense reactions and reflects the occurrence of compartment specific oxidative stress. With immunogold cytochemistry and computer-supported transmission electron microscopy glutathione could be localized in highest contents in mitochondria, followed by nuclei, peroxisomes, the cytosol, and plastids. Within chloroplasts and mitochondria, glutathione was restricted to the stroma and matrix, respectively, and did not occur in the lumen of cristae and thylakoids. Glutathione was also found at the membrane and in the lumen of the endoplasmic reticulum. It was also associated with the trans and cis side of dictyosomes. None or only very little glutathione was detected in vacuoles and the apoplast of mesophyll and root cells. Additionally, glutathione was found in all cell compartments of phloem vessels, vascular parenchyma cells (including vacuoles) but was absent in xylem vessels. The specificity of this method was supported by the reduction of glutathione labeling in all cell compartments (up to 98%) of the glutathione-deficient Arabidopsis thaliana rml1 mutant. Additionally, we found a similar distribution of glutathione in samples after conventional fixation and rapid microwave-supported fixation. Thus, indicating that a redistribution of glutathione does not occur during sample preparation. Summing up, this study gives a detailed insight into the subcellular distribution of glutathione in plants and presents solid evidence for the accuracy and specificity of the applied method.
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Affiliation(s)
- Bernd Zechmann
- Institute of Plant Sciences, University of Graz, Schubertstrasse 51, 8010, Graz, Austria.
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1155
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Mur LAJ, Aubry S, Mondhe M, Kingston-Smith A, Gallagher J, Timms-Taravella E, James C, Papp I, Hörtensteiner S, Thomas H, Ougham H. Accumulation of chlorophyll catabolites photosensitizes the hypersensitive response elicited by Pseudomonas syringae in Arabidopsis. THE NEW PHYTOLOGIST 2010; 188:161-74. [PMID: 20704660 DOI: 10.1111/j.1469-8137.2010.03377.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
• The staygreen (SGR) gene encodes a chloroplast-targeted protein which promotes chlorophyll degradation via disruption of light-harvesting complexes (LHCs). • Over-expression of SGR in Arabidopsis (SGR-OX) in a Columbia-0 (Col-0) background caused spontaneous necrotic flecking. To relate this to the hypersensitive response (HR), Col-0, SGR-OX and RNAi SGR (SGRi) lines were challenged with Pseudomonas syringae pv tomato (Pst) encoding the avirulence gene avrRpm1. Increased and decreased SGR expression, respectively, accelerated and suppressed the kinetics of HR-cell death. In Col-0, SGR transcript increased at 6 h after inoculation (hai) when tissue electrolyte leakage indicated the initiation of cell death. • Excitation of the chlorophyll catabolite pheophorbide (Pheide) leads to the formation of toxic singlet oxygen ((1)O(2)). Pheide was first detected at 6 hai with Pst avrRpm1 and was linked to (1)O(2) generation and correlated with reduced Pheide a oxygenase (PaO) protein concentrations. The maximum quantum efficiency of photosystem II (F(v)/F(m)), quantum yield of electron transfer at photosystem II (φPSII), and photochemical quenching (qP) decreased at 6 hai in Col-0 but not in SGRi. Disruption of photosynthetic electron flow will cause light-dependent H(2)O(2) generation at 6 hai. • We conclude that disruption of LHCs, possibly influenced by SGR, and absence of PaO produce phototoxic chlorophyll catabolites and oxidative stress leading to the HR.
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Affiliation(s)
- Luis A J Mur
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Ceredigion SY23 3DA, UK.
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1156
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Antal TK, Krendeleva TE, Rubin AB. Acclimation of green algae to sulfur deficiency: underlying mechanisms and application for hydrogen production. Appl Microbiol Biotechnol 2010; 89:3-15. [DOI: 10.1007/s00253-010-2879-6] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Revised: 09/02/2010] [Accepted: 09/07/2010] [Indexed: 11/29/2022]
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1157
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Pulido P, Spínola MC, Kirchsteiger K, Guinea M, Pascual MB, Sahrawy M, Sandalio LM, Dietz KJ, González M, Cejudo FJ. Functional analysis of the pathways for 2-Cys peroxiredoxin reduction in Arabidopsis thaliana chloroplasts. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:4043-54. [PMID: 20616155 PMCID: PMC2935875 DOI: 10.1093/jxb/erq218] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 05/25/2010] [Accepted: 06/21/2010] [Indexed: 05/19/2023]
Abstract
Photosynthesis is a process that inevitably produces reactive oxygen species, such as hydrogen peroxide, which is reduced by chloroplast-localized detoxification mechanisms one of which involves 2-Cys peroxiredoxins (2-Cys Prxs). Arabidopsis chloroplasts contain two very similar 2-Cys Prxs (denoted A and B). These enzymes are reduced by two pathways: NADPH thioredoxin reductase C (NTRC), which uses NADPH as source of reducing power; and plastidial thioredoxins (Trxs) coupled to photosynthetically reduced ferredoxin of which Trx chi is the most efficient reductant in vitro. With the aim of establishing the functional relationship between NTRC, Trx x, and 2-Cys Prxs in vivo, an Arabidopsis Trx chi knock-out mutant has been identified and a double mutant (denoted Delta 2cp) with <5% of 2-Cys Prx content has been generated. The phenotypes of the three mutants, ntrc, trxx, and Delta 2cp, were compared under standard growth conditions and in response to continuous light or prolonged darkness and oxidative stress. Though all mutants showed altered redox homeostasis, no difference was observed in response to oxidative stress treatment. Moreover, the redox status of the 2-Cys Prx was imbalanced in the ntrc mutant but not in the trxx mutant. These results show that NTRC is the most relevant pathway for chloroplast 2-Cys Prx reduction in vivo, but the antioxidant function of this system is not essential. The deficiency of NTRC caused a more severe phenotype than the deficiency of Trx chi or 2-Cys Prxs as determined by growth, pigment content, CO(2) fixation, and F(v)/F(m), indicating additional functions of NTRC.
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Affiliation(s)
- Pablo Pulido
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla and CSIC, Avda Américo Vespucio 49, 41092-Sevilla, Spain
| | - María Cristina Spínola
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla and CSIC, Avda Américo Vespucio 49, 41092-Sevilla, Spain
| | - Kerstin Kirchsteiger
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla and CSIC, Avda Américo Vespucio 49, 41092-Sevilla, Spain
| | - Manuel Guinea
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla and CSIC, Avda Américo Vespucio 49, 41092-Sevilla, Spain
| | - María Belén Pascual
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla and CSIC, Avda Américo Vespucio 49, 41092-Sevilla, Spain
| | - Mariam Sahrawy
- Departamento de Bioquímica y Biología Molecular de Plantas, Estación Experimental del Zaidín, CSIC, C/Profesor Alvareda, 18008-Granada, Spain
| | - Luisa María Sandalio
- Departamento de Bioquímica y Biología Molecular de Plantas, Estación Experimental del Zaidín, CSIC, C/Profesor Alvareda, 18008-Granada, Spain
| | - Karl-Josef Dietz
- Biochemistry and Physiology of Plants, W5-134, Bielefeld University, D-33501, Germany
| | - Maricruz González
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla and CSIC, Avda Américo Vespucio 49, 41092-Sevilla, Spain
| | - Francisco Javier Cejudo
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla and CSIC, Avda Américo Vespucio 49, 41092-Sevilla, Spain
- To whom correspondence should be addressed. E-mail:
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1158
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Gorsuch PA, Sargeant AW, Penfield SD, Quick WP, Atkin OK. Systemic low temperature signaling in Arabidopsis. PLANT & CELL PHYSIOLOGY 2010; 51:1488-1498. [PMID: 20813832 DOI: 10.1093/pcp/pcq112] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
When leaves are exposed to low temperature, sugars accumulate and transcription factors in the C-repeat binding factor (CBF) family are expressed, which, together with CBF-independent pathways, are known to contribute to the cold acclimation process and an increase in freezing tolerance. What is not known, however, is whether expression of these cold-regulated genes can be induced systemically in response to a localized cold treatment. To address this, pre-existing, mature leaves of warm-grown Arabidopsis thaliana were exposed to a localized cold treatment (near 10 °C) whilst conjoined newly developing leaves continued only to experience warmer temperatures. In initial experiments on wild-type A. thaliana (Col-0) using real-time reverse transcription--PCR (RT-PCR) we observed that some genes--including CBF genes, certain downstream cold-responsive (COR) targets and CBF-independent transcription factors--respond to a direct 9 °C treatment of whole plants. In subsequent experiments, we found that the treatment of expanded leaves with temperatures near 10 °C can induce cold-associated genes in conjoined warm-maintained tissues. CBF1 showed a particularly strong systemic response, although CBF-independent transcription factors also responded. Moreover, the localized cold treatment of A. thaliana (C24) plants with a luciferase reporter fused to the promoter region of KIN2 indicated that in warm-maintained leaves, KIN2 might respond to a systemic signal from remote, directly cold-treated leaves. Collectively, our study provides strong evidence that the processes involved in cold acclimation are partially mediated by a signal that acts systemically. This has the potential to act as an early-warning system to enable developing leaves to cope better with the cold environment in which they are growing.
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Affiliation(s)
- Peter A Gorsuch
- Department of Biology, University of York, PO Box 373, York YO105YW, UK
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1159
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Antal T, Mattila H, Hakala-Yatkin M, Tyystjärvi T, Tyystjärvi E. Acclimation of photosynthesis to nitrogen deficiency in Phaseolus vulgaris. PLANTA 2010; 232:887-98. [PMID: 20632184 DOI: 10.1007/s00425-010-1227-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Accepted: 07/06/2010] [Indexed: 05/22/2023]
Abstract
Nitrogen deficiency diminishes consumption of photosynthates in anabolic metabolism. We studied adjustments of the photosynthetic machinery in nitrogen-deficient bean plants and found four phenomena. First, the number of chloroplasts per cell decreased. Chloroplasts of nitrogen starved leaves contained less pigments than those of control leaves, but the in vitro activities of light reactions did not change when measured on chlorophyll basis. Second, nitrogen deficiency induced cyclic electron transfer. The amounts of Rubisco and ferredoxin-NADP(+) reductase decreased in nitrogen starved plants. Low activities of these enzymes are expected to lead to increase in reduction of oxygen by photosystem I. However, diaminobenzidine staining did not reveal hydrogen peroxide production in nitrogen starved plants. Measurements of far-red-light-induced redox changes of the primary donor of photosystem I suggested that instead of producing oxygen radicals, nitrogen starved plants develop a high activity of cyclic electron transport that competes with oxygen for electrons. Nitrogen starvation led to decrease in photochemical quenching and increase in non-photochemical quenching, indicating that cyclic electron transport reduces the plastoquinone pool and acidifies the lumen. A third effect is redistribution of excitation energy between the photosystems in favor of photosystem I. Thus, thylakoids of nitrogen starved plants appeared to be locked in state 2, which further protects photosystem II by decreasing its absorption cross-section. As a fourth response, the proportion of non-Q(B)-reducing photosystem II reaction centers increased and the redox potential of the Q(B)/Q(B)(-) pair decreased by 25 mV in a fraction of photosystem II centers of nitrogen starved plants.
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Affiliation(s)
- Taras Antal
- Molecular Plant Biology, Department of Biochemistry and Food Chemistry, University of Turku, Turku, Finland
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1160
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Selote DS, Khanna-Chopra R. Antioxidant response of wheat roots to drought acclimation. PROTOPLASMA 2010; 245:153-63. [PMID: 20559854 DOI: 10.1007/s00709-010-0169-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2010] [Accepted: 05/26/2010] [Indexed: 05/21/2023]
Abstract
Wheat (Triticum aestivum L.) seedlings of a drought-resistant cv. C306 were subjected to severe water deficit directly or through stress cycles of increasing intensity with intermittent recovery periods. The antioxidant defense in terms of redox metabolites and enzymes in root cells and mitochondria was examined in relation to membrane damage. Acclimated seedlings exhibited higher relative water content and were able to limit the accumulation of H(2)O(2) and membrane damage during subsequent severe water stress conditions. This was due to systematic up-regulation of superoxide dismutase, ascorbate peroxidase (APX), catalase, peroxidases, and ascorbate-glutathione cycle components at both the whole cell level as well as in mitochondria. In contrast, direct exposure of severe water stress to non-acclimated seedlings caused greater water loss, excessive accumulation of H(2)O(2) followed by elevated lipid peroxidation due to the poor antioxidant enzyme response particularly of APX, monodehydroascorbate reductase, dehydroascorbate reductase, glutathione reductase, and ascorbate-glutathione redox balance. Mitochondrial antioxidant defense was found to be better than the cellular defense in non-acclimated roots. Termination of stress followed by rewatering leads to a rapid enhancement in all the antioxidant defense components in non-acclimated roots, which suggested that the excess levels of H(2)O(2) during severe water stress conditions might have inhibited or down-regulated the antioxidant enzymes. Hence, drought acclimation conferred enhanced tolerance toward oxidative stress in the root tissue of wheat seedlings due to both reactive oxygen species restriction and well-coordinated induction of antioxidant defense.
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Affiliation(s)
- Devarshi S Selote
- Stress Physiology Laboratory, Water Technology Centre, Indian Agricultural Research Institute, New Delhi, 110012, India
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1161
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Yin Y, Li S, Liao W, Lu Q, Wen X, Lu C. Photosystem II photochemistry, photoinhibition, and the xanthophyll cycle in heat-stressed rice leaves. JOURNAL OF PLANT PHYSIOLOGY 2010; 167:959-66. [PMID: 20417985 DOI: 10.1016/j.jplph.2009.12.021] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Revised: 12/11/2009] [Accepted: 12/14/2009] [Indexed: 05/22/2023]
Abstract
To investigate how high light affects the responses of photosynthesis to heat stress, the effects of high temperature (25-42.5 degrees C) either in the dark or in the light (1000 micromol m(-2) s(-1)) on photosystem II (PSII) photochemistry and the xanthophyll cycle were investigated in rice plants. At temperatures higher than 35 degrees C, there was a decrease in the CO(2) assimilation rate, and this decrease was greater in the light than in the dark. The maximal efficiency of PSII photochemistry (F(v)/F(m)) showed no significant change in the dark, but did show a significant decrease in the light. In addition, there was an increase in non-photochemical quenching (NPQ) and this increase was greater in the light than in the dark. Furthermore, the de-epoxidation status of the xanthophyll cycle increased significantly with increasing temperature in the light. Compared to the control leaves, the dithiothreitol-fed leaves showed a greater decrease in F(v)/F(m) but a very small increase in NPQ and de-epoxidation status of the xanthophyll cycle at temperatures higher than 35 degrees C. On the other hand, the ascorbate-fed leaves showed less of a decrease in F(v)/F(m) but a greater increase in NPQ and the de-epoxidation status of the xanthophyll cycle. Ascorbate peroxidase and glutathione reductase activities in leaves and chloroplasts were enhanced and this enhancement was greater in the light than in the dark. Heat stress had no significant effect on the contents of ascorbate and glutathione in leaves and chloroplasts in the dark, but led to an increase in the contents of reduced ascorbate and glutathione in leaves and chloroplasts in the light at the temperatures higher than 35 degrees C. Our results suggest that the xanthophyll cycle plays an important role in protecting PSII against heat-induced photoinhibition by an increase in the ascorbate pool in the chloroplast.
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Affiliation(s)
- Yan Yin
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, PR China
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1162
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Chlorella vulgaris aldehyde reductase is capable of functioning as ferric reductase and of driving the fenton reaction in the presence of free flavin. Biosci Biotechnol Biochem 2010; 74:854-7. [PMID: 20445323 DOI: 10.1271/bbb.90798] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The free flavin-dependent Fenton reaction was detected in cell-free extracts of Chlorella. The corresponding enzyme was purified to homogeneity, and its N-terminal sequence was highly homologous to those of aldo-keto reductase family enzymes. The purified enzyme displayed aldehyde reductase activity in the presence of NADPH. Additionally, it showed ferric reductase activity and drove the Fenton reaction in the presence of free FAD and NADH.
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1163
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Majer P, Stoyanova S, Hideg E. Do leaf total antioxidant capacities (TAC) reflect specific antioxidant potentials? - A comparison of TAC and reactive oxygen scavenging in tobacco leaf extracts. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2010; 100:38-43. [PMID: 20547070 DOI: 10.1016/j.jphotobiol.2010.04.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 04/22/2010] [Accepted: 04/27/2010] [Indexed: 11/16/2022]
Abstract
Two traditional methods of total antioxidant capacity (TAC) assessment, Trolox equivalent antioxidant capacity (TEAC) and ferric reducing antioxidant power (FRAP) were applied to water extracts from tobacco leaves at various stages of senescence. Physiological status of the leaves was characterized by the effective photochemical quantum yield of photosynthesis (Y(II)). TAC values were compared to amounts of total phenolics, carotenoid contents and also to reactive oxygen scavenging capacities of the leaf extracts. To this end a new, simple fluorimetric assay was introduced for testing hydroxyl radical neutralizing capacity in leaf extracts. We found that while both TAC values increased with declining photosynthesis and decreasing pigment content, they were not characteristic to specific superoxide or hydroxyl radical scavenging and had limited connection to leaf antioxidant content. Good linear correlations were only found between the following pairs of parameters: Y(II) - total carotenoid, TEAC - total carotenoid, FRAP - total phenolics. Our data show that TEAC and FRAP are not interchangeable in leaf studies and do not represent antioxidant action on ROS.
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Affiliation(s)
- Petra Majer
- Institute of Plant Biology, Biological Research Center, Szeged, Hungary
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1164
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Møller IM, Sweetlove LJ. ROS signalling--specificity is required. TRENDS IN PLANT SCIENCE 2010; 15:370-4. [PMID: 20605736 DOI: 10.1016/j.tplants.2010.04.008] [Citation(s) in RCA: 237] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 04/26/2010] [Accepted: 04/29/2010] [Indexed: 05/19/2023]
Abstract
Reactive oxygen species (ROS) production increases in plants under stress. ROS can damage cellular components, but they can also act in signal transduction to help the cell counteract the oxidative damage in the stressed compartment. H(2)O(2) might induce a general stress response, but it does not have the required specificity to selectively regulate nuclear genes required for dealing with localized stress, e.g. in chloroplasts or mitochondria. Here we argue that peptides deriving from proteolytic breakdown of oxidatively damaged proteins have the requisite specificity to act as secondary ROS messengers and regulate source-specific genes and in this way contribute to retrograde ROS signalling during oxidative stress. Likewise, unmodified peptides deriving from the breakdown of redundant proteins could help coordinate organellar and nuclear gene expression.
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Affiliation(s)
- Ian M Møller
- Department of Genetics and Biotechnology, Faculty of Agricultural Sciences, Aarhus University, Forsøgsvej 1, DK-4200 Slagelse, Denmark.
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1165
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Hůnová I, Novotný R, Uhlírová H, Vráblík T, Horálek J, Lomský B, Srámek V. The impact of ambient ozone on mountain spruce forests in the Czech Republic as indicated by malondialdehyde. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2010; 158:2393-2401. [PMID: 20466470 DOI: 10.1016/j.envpol.2010.04.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Revised: 04/02/2010] [Accepted: 04/13/2010] [Indexed: 05/29/2023]
Abstract
Malondialdehyde (MDA), a product of lipid peroxidation and biomarker of oxidative stress, is measured over the long term in spruce Picea abies needles under real conditions in three Czech mountain border areas. The trends presented collate the MDA content in spruce needles with ambient ozone, temperature and precipitation as casual, and defoliation as a subsequent factor for the period 1994-2006. We have found the overall decreasing trends in MDA and defoliation. The highest MDA and defoliation are recorded in the Jizerske, the lowest in the Krusne hory Mts. Out of the examined variables the MDA is predicted best by mean temperature in vegetation season, median of O(3) concentrations and AOT40; these three variables account for 34% of MDA1 and 36% of MDA2 variability. Our hypothesis that higher ambient O(3) exposure results in higher MDA contents in P. abies needles under real conditions has not been approved.
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Affiliation(s)
- Iva Hůnová
- Czech Hydrometeorological Institute, Na Sabatce 17, 143 06 Prague 4-Komorany, Czech Republic.
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1166
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Lin KH, Huang HC, Lin CY. Cloning, expression and physiological analysis of broccoli catalase gene and Chinese cabbage ascorbate peroxidase gene under heat stress. PLANT CELL REPORTS 2010; 29:575-93. [PMID: 20352229 DOI: 10.1007/s00299-010-0846-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 03/06/2010] [Accepted: 03/16/2010] [Indexed: 05/04/2023]
Abstract
The objectives of this work were to clone the catalase (CAT) gene from broccoli (Brassica oleracea) and the ascorbate peroxidase (APX) gene from Chinese cabbage and measure the regulation of CAT and APX gene expressions under heat-stress conditions. Different genotypes responded differently to heat stress according to their various antioxidant enzymes and physiological parameters. CAT and APX gene expression profiles were well matched with the data for CAT and APX enzyme activities in the broccoli and Chinese cabbage plants, respectively. Full-length of the CAT and APX cDNA were 1,768 and 1,070 bp, respectively. A phylogenetic analysis of CAT and APX indicated that plant CATs and APXs diverged into two major clusters.
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Affiliation(s)
- Kuan-Hung Lin
- Graduate Institute of Biotechnology, Chinese Culture University, 55 Hwa-Kong Road, Taipei, 111, Taiwan, ROC.
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1167
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Sakuraba Y, Yokono M, Akimoto S, Tanaka R, Tanaka A. Deregulated chlorophyll b synthesis reduces the energy transfer rate between photosynthetic pigments and induces photodamage in Arabidopsis thaliana. PLANT & CELL PHYSIOLOGY 2010; 51:1055-65. [PMID: 20403808 DOI: 10.1093/pcp/pcq050] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Chl b is one of the major light-harvesting pigments in land plants. The synthesis of Chl b is strictly regulated in response to light conditions in order to control the antenna size of photosystems. Regulation of Chl b also affects its distribution as it occurs preferentially in the peripheral antenna complexes. However, it has not been experimentally shown how plants respond to environmental conditions when they accumulate excess Chl b. Previously, we produced an Arabidopsis transgenic plant (referred to as the BC plant) in which Chl b biosynthesis was enhanced. In this study, we analyzed the photosynthetic properties and genome-wide gene expression in this plant under high light conditions in order to understand the effects of deregulated Chl b biosynthesis. The energy transfer rates between Chl a molecules in PSII decreased and H(2)O(2) accumulated extensively in the BC plant. Microarray analysis revealed that a group of genes involved in anthocyanin biosynthesis was down-regulated and that another group of genes, reported to be sensitive to H(2)O(2), was up-regulated in the BC plant. We also found that anthocyanin levels were low, which was consistent with the results of the microarray analysis. These results indicate that deregulation of Chl b caused severe photodamage and altered gene expression profiles under strong illumination. The importance of the regulation of Chl b synthesis is discussed in relation to the correct localization of Chl b and gene expression.
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Affiliation(s)
- Yasuhito Sakuraba
- Institute of Low Temperature Science, Hokkaido University, N19 W8, Kita-ku, Sapporo, 060-0819 Japan
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1168
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Falk J, Munné-Bosch S. Tocochromanol functions in plants: antioxidation and beyond. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:1549-66. [PMID: 20385544 DOI: 10.1093/jxb/erq030] [Citation(s) in RCA: 171] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Tocopherols and tocotrienols, collectively known as tocochromanols, are lipid-soluble molecules that belong to the group of vitamin E compounds and are essential in the human diet. Not surprisingly, most of what is known about the biological functions of tocochromanols comes from studies of mammalian systems, yet they have been shown to be synthesized only by photosynthetic organisms. The last decade has seen a radical change in the appreciation of the biological role of tocochromanols in plants thanks to a detailed characterization of mutant and transgenic plants, including several Arabidopsis thaliana mutants, the sucrose export defective1 (sxd1) maize mutant, and some transgenic potato and tobacco lines altered in tocochromanol biosynthesis. Recent findings indicate that tocopherols may play important roles in plants beyond their antioxidant function in photosynthetic membranes. Plants deficient in tocopherols show alterations in germination and export of photoassimilates, and growth, leaf senescence, and plant responses to abiotic stresses, thus suggesting that tocopherols may influence a number of physiological processes in plants. Thus, in this review not only the antioxidant function of tocochromanols in plants, but also these new emerging possible roles will be considered. Particular attention will be paid to specific roles attributed to different tocopherol homologues (particularly alpha- and gamma-tocopherol) and the possible functions of tocotrienols, which in contrast to tocopherols are only present in a range of unrelated plant groups and are almost exclusively found in seeds and fruits.
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Affiliation(s)
- Jon Falk
- Carlsberg Research Center, 10 Gamle Carlsberg Vej, DK-2500 Valby, Denmark
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1169
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González-Ballester D, Casero D, Cokus S, Pellegrini M, Merchant SS, Grossman AR. RNA-seq analysis of sulfur-deprived Chlamydomonas cells reveals aspects of acclimation critical for cell survival. THE PLANT CELL 2010; 22:2058-84. [PMID: 20587772 PMCID: PMC2910963 DOI: 10.1105/tpc.109.071167] [Citation(s) in RCA: 195] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Revised: 04/01/2010] [Accepted: 05/18/2010] [Indexed: 05/18/2023]
Abstract
The Chlamydomonas reinhardtii transcriptome was characterized from nutrient-replete and sulfur-depleted wild-type and snrk2.1 mutant cells. This mutant is null for the regulatory Ser-Thr kinase SNRK2.1, which is required for acclimation of the alga to sulfur deprivation. The transcriptome analyses used microarray hybridization and RNA-seq technology. Quantitative RT-PCR evaluation of the results obtained by these techniques showed that RNA-seq reports a larger dynamic range of expression levels than do microarray hybridizations. Transcripts responsive to sulfur deprivation included those encoding proteins involved in sulfur acquisition and assimilation, synthesis of sulfur-containing metabolites, Cys degradation, and sulfur recycling. Furthermore, we noted potential modifications of cellular structures during sulfur deprivation, including the cell wall and complexes associated with the photosynthetic apparatus. Moreover, the data suggest that sulfur-deprived cells accumulate proteins with fewer sulfur-containing amino acids. Most of the sulfur deprivation responses are controlled by the SNRK2.1 protein kinase. The snrk2.1 mutant exhibits a set of unique responses during both sulfur-replete and sulfur-depleted conditions that are not observed in wild-type cells; the inability of this mutant to acclimate to S deprivation probably leads to elevated levels of singlet oxygen and severe oxidative stress, which ultimately causes cell death. The transcriptome results for wild-type and mutant cells strongly suggest the occurrence of massive changes in cellular physiology and metabolism as cells become depleted for sulfur and reveal aspects of acclimation that are likely critical for cell survival.
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1170
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Sigma factor phosphorylation in the photosynthetic control of photosystem stoichiometry. Proc Natl Acad Sci U S A 2010; 107:10760-4. [PMID: 20498041 DOI: 10.1073/pnas.0911692107] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
An imbalance in photosynthetic electron transfer is thought to be redressed by photosynthetic control of the rate of expression of genes encoding apoproteins of photosystem (PS)-I and PS-II in response to the redox state of plastoquinone (PQ), which is a connecting electron carrier. PS stoichiometry is then adjusted to enhance photosynthetic efficiency. In prokaryotes, sigma factors are well known for their participation in the control of RNA polymerase activity in transcription, whereas there have been no reports concerning their association with redox regulation. We have found that the phosphorylation of SIG1, the major sigma factor (SIG), is regulated by redox signals and selectively inhibits the transcription of the psaA gene, which encodes a PS-I protein. We produced transgenic Arabidopsis plants with or without the putative phosphorylation sites for SIG1 and demonstrated through in vivo labeling that Thr-170 was involved in the phosphorylation. We analyzed the in vivo and in vitro transcriptional responses of the transgenic Arabidopsis plants to the redox status in regard to involvement of the phosphorylation site. We revealed an enhanced phosphorylation of SIG1 under oxidative conditions of PQ in a form associated with the molecular mass of the holoenzyme. Phosphorylation of SIG1 proved crucial through a change in the promoter specificity for sustaining balanced expression of components in PS-I and PS-II and was responsible for harmonious electron flow to maintain photosynthetic efficiency.
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1171
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Straus MR, Rietz S, Ver Loren van Themaat E, Bartsch M, Parker JE. Salicylic acid antagonism of EDS1-driven cell death is important for immune and oxidative stress responses in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 62:628-40. [PMID: 20163553 DOI: 10.1111/j.1365-313x.2010.04178.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Reactive oxygen species (ROS) have emerged as signals in the responses of plants to stress. Arabidopsis Enhanced Disease Susceptibility1 (EDS1) regulates defense and cell death against biotrophic pathogens and controls cell death propagation in response to chloroplast-derived ROS. Arabidopsis Nudix hydrolase7 (nudt7) mutants are sensitized to photo-oxidative stress and display EDS1-dependent enhanced resistance, salicylic acid (SA) accumulation and initiation of cell death. Here we explored the relationship between EDS1, EDS1-regulated SA and ROS by examining gene expression profiles, photo-oxidative stress and resistance phenotypes of nudt7 mutants in combination with eds1 and the SA-biosynthetic mutant, sid2. We establish that EDS1 controls steps downstream of chloroplast-derived O(2)(*-) that lead to SA-assisted H(2)O(2) accumulation as part of a mechanism limiting cell death. A combination of EDS1-regulated SA-antagonized and SA-promoted processes is necessary for resistance to host-adapted pathogens and for a balanced response to photo-oxidative stress. In contrast to SA, the apoplastic ROS-producing enzyme NADPH oxidase RbohD promotes initiation of cell death during photo-oxidative stress. Thus, chloroplastic O(2)(*-) signals are processed by EDS1 to produce counter-balancing activities of SA and RbohD in the control of cell death. Our data strengthen the idea that EDS1 responds to the status of O(2)(*-) or O(2)(*-)-generated molecules to coordinate cell death and defense outputs. This activity may enable the plant to respond flexibly to different biotic and abiotic stresses in the environment.
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Affiliation(s)
- Marco R Straus
- Max-Planck-Institute for Plant Breeding Research, Carl-von-Linne-Weg 10, 50829 Köln, Germany
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1172
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Kiselevsky DB, Kuznetsova YE, Vasil'ev LA, Lobysheva NV, Zinovkin RA, Nesov AV, Shestak AA, Samuilov VD. Effect of Ca2+ on programmed death of guard and epidermal cells of pea leaves. BIOCHEMISTRY. BIOKHIMIIA 2010; 75:614-22. [PMID: 20632941 DOI: 10.1134/s0006297910050111] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
The effect of Ca2+ on programmed death of guard cells (GC) and epidermal cells (EC) determined from destruction of the cell nucleus was investigated in epidermis of pea leaves. Ca2+ at concentrations of 1-100 microM increased and at a concentration of 1 mM prevented the CN(-)-induced destruction of the nucleus in GC, disrupting the permeability barrier of GC plasma membrane for propidium iodide (PI). Ca2+ at concentrations of 0.1-1 mM enhanced drastically the number of EC nuclei stained by PI in epidermis treated with chitosan, an inducer of programmed cell death. The internucleosomal DNA fragmentation caused by CN(-) was suppressed by 2 mM Ca2+ on 6 h incubation, but fragmentation was stimulated on more prolonged treatment (16 h). Presumably, the disruption of the permeability barrier of plasma membrane for PI is not a sign of necrosis in plant cells. Quinacrine and diphenylene iodonium at 50 microM concentration prevented GC death induced by CN(-) or CN(-) + 0.1 mM Ca2+ but had no influence on respiration and photosynthetic O2 evolution in pea leaf slices. The generation of reactive oxygen species determined from 2',7'-dichlorofluorescein fluorescence was promoted by Ca2+ in epidermal peels from pea leaves.
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Affiliation(s)
- D B Kiselevsky
- Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
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1173
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Miura E, Kato Y, Sakamoto W. Comparative transcriptome analysis of green/white variegated sectors in Arabidopsis yellow variegated2: responses to oxidative and other stresses in white sectors. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:2433-45. [PMID: 20400527 PMCID: PMC2877895 DOI: 10.1093/jxb/erq075] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Revised: 03/05/2010] [Accepted: 03/08/2010] [Indexed: 05/20/2023]
Abstract
The yellow variegated2 (var2) mutant in Arabidopsis thaliana has been studied as a typical leaf-variegated mutant whose defect results from the lack of FtsH2 metalloprotease in chloroplasts. The var2 green sectors suffer from photo-oxidative stress and accumulate high levels of reactive oxygen species (ROS) because of compromised Photosystem II repair. This study investigated and compared microarray-based expression profiles of green and white sectors of var2 leaves. Results suggest that ROS that accumulate in chloroplasts of var2 green sectors do not cause much significant change in the transcriptional profile related to ROS signalling and scavenging. By contrast, transcriptome in the white sectors apparently differs from those in the green sectors and wild type. Numerous genes related to photosynthesis and chloroplast functions were repressed in the white sectors. Furthermore, many genes related to oxidative stress were up-regulated. Among them, ROS scavenging genes were specifically examined, such as Cu/Zn superoxide dismutase 2 (CSD2), that were apparently up-regulated in white but not in the green sectors. Up-regulation of CSD2 appears to be partly attributable to the lack of a microRNA (miR398) in the white sectors. It was concluded that the white sectors exhibit a response to oxidative and other stresses, including CSD2 up-regulation, which might be commonly found in tissues with abnormal chloroplast differentiation.
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1174
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Xu Y, Sun X, Jin J, Zhou H. Protective effect of nitric oxide on light-induced oxidative damage in leaves of tall fescue. JOURNAL OF PLANT PHYSIOLOGY 2010; 167:512-8. [PMID: 19931209 DOI: 10.1016/j.jplph.2009.10.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2009] [Revised: 10/26/2009] [Accepted: 10/26/2009] [Indexed: 05/06/2023]
Abstract
Nitric oxide (NO) is an important signaling molecule involved in many physiological processes. In this study, the effect of NO on oxidative damage caused by high levels of light was investigated in leaves of two varieties of tall fescue (Arid3 and Houndog5). Leaves of Houndog5 were more susceptible to high-light stress than Arid3 leaves. Pretreatment of these leaves with NO donor sodium nitroprusside (SNP), prior to exposure to high-light stress, resulted in reduced light-induced electrolyte leakage and reduced contents of malondialdehyde, hydrogen peroxide (H(2)O(2)) and superoxide radicals (O(2)(*-)). The activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) increased in both varieties in the presence of SNP under high-light stress, but lipoxygenase (LOX) activity was inhibited. These responses could be reversed by pretreatment with the NO scavenger 2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). A pronounced increase in nitric oxide synthase (NOS) activity and NO release was found in light-tolerant Arid3 plants after exposure to high-light stress, while only a small increase was observed in more sensitive Houndog5. Pretreatment with the NOS inhibitor N(omega)-nitro-l-arginine (LNNA) resulted in increased oxidative damage under high-light stress, with more injuries occurring in Arid3 than Houndog5. These results suggest that high-light stress induced increased NOS activity leading to elevated NO. This NO might act as a signaling molecule triggering enhanced activities of antioxidant enzymes, further protecting against injuries caused by high intensity light. This protective mechanism was found to more efficiently acclimate light-tolerant Arid3 than light-sensitive Houndog5.
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Affiliation(s)
- Yuefei Xu
- Department of Grassland Science, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
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1175
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Nielsen HD, Nielsen SL. Adaptation to high light irradiances enhances the photosynthetic Cu2+ resistance in Cu2+ tolerant and non-tolerant populations of the brown macroalgae Fucus serratus. MARINE POLLUTION BULLETIN 2010; 60:710-7. [PMID: 20060134 DOI: 10.1016/j.marpolbul.2009.11.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Revised: 11/26/2009] [Accepted: 11/29/2009] [Indexed: 05/05/2023]
Abstract
The relationship between light acclimation and Cu(2+) tolerance was studied in two populations of Fucus serratus known to be naturally non-tolerant and tolerant to Cu(2+). Acclimation to high irradiances increased the photosynthetic tolerance to Cu(2+). The xanthophyll cycle was apparently not involved in protecting the photosynthetic apparatus against Cu(2+) toxicity, as results showed that Cu(2+) did not induce dynamic photoinhibition. The higher photosynthetic Cu(2+) resistance of high light algae did not result in increased growth. The excess energy acquired by high light-adapted algae appeared to be utilized in Cu(2+) defense mechanisms in the Cu(2+) non-tolerant population. The polyphenol content of the algae was reciprocal to the Cu(T) content, suggesting that polyphenol may be the primary Cu(2+) defense of non-tolerant low light algae, acting through secretion and extracellular chelating of Cu(2+), while the compounds do not seem to be involved in the primary Cu(2+) tolerance mechanism in Cu(2+) tolerant algae.
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Affiliation(s)
- Hanne Dalsgaard Nielsen
- School of Life Sciences, Napier University, 10 Colinton Road, Edinburgh EH10 5DT, United Kingdom
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1176
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Abstract
Production of reactive oxygen species (ROS) is a hallmark of successful recognition of infection and activation of plant defenses. ROS play multifaceted signaling functions mediating the establishment of multiple responses and can act as local toxins. Controversy surrounds the origin of these ROS. Several enzymatic mechanisms, among them a plasma membrane NADPH oxidase and cell wall peroxidases, can be responsible for the ROS detected in the apoplast. However, high levels of ROS from metabolic origins and/or from downregulation of ROS-scavenging systems can also accumulate in different compartments of the plant cell. This compartmentalization could contribute to the specific functions attributed to ROS. Additionally, ROS interact with other signals and phytohormones, which could explain the variety of different scenarios where ROS signaling plays an important part. Interestingly, pathogens have developed ways to alter ROS accumulation or signaling to modify plant defenses. Although ROS have been mainly associated with pathogen attack, ROS are also detected in other biotic interactions including beneficial symbiotic interactions with bacteria or mycorrhiza, suggesting that ROS production is a common feature of different biotic interactions. Here, we present a comprehensive review describing the newer views in ROS signaling and function during biotic stress.
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Affiliation(s)
- Miguel Angel Torres
- Centro de Biotecnología y Genómica de Plantas (UPM, INIA), Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Campus Montegancedo, Autopista M40 Km 38, Pozuelo de Alarcón, 28223, Madrid, Spain.
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1177
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Miller G, Suzuki N, Ciftci-Yilmaz S, Mittler R. Reactive oxygen species homeostasis and signalling during drought and salinity stresses. PLANT, CELL & ENVIRONMENT 2010; 33:453-67. [PMID: 19712065 DOI: 10.1111/j.1365-3040.2009.02041.x] [Citation(s) in RCA: 1705] [Impact Index Per Article: 121.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Water deficit and salinity, especially under high light intensity or in combination with other stresses, disrupt photosynthesis and increase photorespiration, altering the normal homeostasis of cells and cause an increased production of reactive oxygen species (ROS). ROS play a dual role in the response of plants to abiotic stresses functioning as toxic by-products of stress metabolism, as well as important signal transduction molecules. In this review, we provide an overview of ROS homeostasis and signalling in response to drought and salt stresses and discuss the current understanding of ROS involvement in stress sensing, stress signalling and regulation of acclimation responses.
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Affiliation(s)
- Gad Miller
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, 89557, USA
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1178
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Galvez-Valdivieso G, Mullineaux PM. The role of reactive oxygen species in signalling from chloroplasts to the nucleus. PHYSIOLOGIA PLANTARUM 2010; 138:430-9. [PMID: 20028481 DOI: 10.1111/j.1399-3054.2009.01331.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The coordination of chloroplast function with the rest of cellular activity requires a continual stream of communication from this organelle to the nucleus. Chloroplasts are major sites of the production of reactive oxygen species (ROS) as either by-products of the reduction of molecular oxygen (O(2)) or its excitation in the presence of highly energised pigments. Such ROS, while potentially damaging to the cell, are also important initiators or transducers of signals from these organelles to the nucleus in response to environmental cues. ROS can initiate such retrograde signalling pathways that trigger either programmed cell death or adjustment to changed conditions. Such different outcomes have implications for the way in which signal transduction by ROS is accomplished and is the subject of this review. In response to mild-stress situations, and as a consequence of their reactivity or because of their containment by cellular antioxidant systems, it is proposed that ROS engage with or initiate signalling at or very near their site of production. In contrast, under more extreme conditions, ROS are proposed to diffuse away from their site of production and consequently elicit a different set of signalling events.
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1179
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Zurbriggen MD, Carrillo N, Hajirezaei MR. ROS signaling in the hypersensitive response: when, where and what for? PLANT SIGNALING & BEHAVIOR 2010; 5:393-6. [PMID: 20383072 PMCID: PMC2958590 DOI: 10.4161/psb.5.4.10793] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Accepted: 11/26/2009] [Indexed: 05/19/2023]
Abstract
Plants generally react to the attack of non-host and incompatible host microorganisms by inducing pathogenesis-related (PR) genes and localised cell death (LCD) at the site of infection, a process collectively known as the hypersensitive response (HR). Reactive oxygen species (ROS) are generated in various sub-cellular compartments shortly after pathogen recognition, and proposed to cue subsequent orchestration of the HR. Although apoplast-associated ROS production by plasma membrane NADPH oxidases have been most thoroughly studied, recent observations suggest that ROS are generated in chloroplasts earlier in the response and play a key role in execution of LCD. A model is presented in which the initial outcome of successful pathogen detection is ROS accumulation in plastids, likely mediated by mitogen-activated protein kinases and caused by dysfunction of the photosynthetic electron transport chain. ROS signaling is proposed to spread from plastids to the apoplast, through the activation of NADPH oxidases, and from there to adjacent cells, leading to suicidal death in the region of attempted infection.
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Affiliation(s)
- Matias D Zurbriggen
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET); Universidad Nacional de Rosario; Rosario, Argentina
| | - Néstor Carrillo
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET); Universidad Nacional de Rosario; Rosario, Argentina
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1180
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Gholizadeh A. Anti-Oxidation Profile in the Leaves of Maize Inbreds: Elevation in the Activity of Phenylalanine Ammonia Lyase under Drought Stress. ACTA ACUST UNITED AC 2010. [DOI: 10.3923/jps.2010.137.145] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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1181
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Darehshouri A, Lütz-Meindl U. H2O2 localization in the green alga Micrasterias after salt and osmotic stress by TEM-coupled electron energy loss spectroscopy. PROTOPLASMA 2010; 239:49-56. [PMID: 19902325 PMCID: PMC2826641 DOI: 10.1007/s00709-009-0081-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Accepted: 10/19/2009] [Indexed: 05/24/2023]
Abstract
Reactive oxygen species (ROS), including hydrogen peroxide (H(2)O(2)), are constantly generated as by-products of normal metabolic cellular pathways and can be overproduced in response to stress. In this study, we investigated ROS production and localization of H(2)O(2) after salt (200 mM KCl) and osmotic (iso-osmotic sorbitol concentration) stress in the unicellular green alga Micrasterias. By means of the dye H(2)DCFDA and confocal laser scanning microscopy, most ROS production could be detected in KCl-treated cells when compared to sorbitol-exposed cells and controls. For ultrastructural detection of H(2)O(2), CeCl(3), which reacts with H(2)O(2) and produces cerium perhydroxide deposits, has been used. Cerium was identified by transmission electron microscopy (TEM)-coupled electron energy loss spectroscopy (EELS) in organelles of KCl- and sorbitol-treated cells and in controls. Statistical measurements of the presence of the cerium M(4,5) edge were performed in mitochondria, chloroplasts, cell walls, and cytoplasmic sites of five individual cells after each treatment. The most pronounced increase in H(2)O(2) production was found in chloroplasts of KCl- and sorbitol-treated cells. This shows that the chloroplast reveals the strongest response in H(2)O(2) production after stress induction in Micrasterias. Significant elevation of H(2)O(2) production also occurred in mitochondria and cytoplasm, whereas H(2)O(2) levels remained unchanged or even slightly decreased in cell walls of treated cells. Additionally, TEM micrographs and EELS analyses provided indirect evidence for an increased H(2)O(2) production at the plasma membrane of KCl-treated cells, indicating an involvement of the plasma membrane NADPH oxidase in H(2)O(2) generation.
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Affiliation(s)
- Anza Darehshouri
- Plant Physiology Division, Cell Biology Department, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria
- Present Address: Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309 USA
| | - Ursula Lütz-Meindl
- Plant Physiology Division, Cell Biology Department, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria
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1182
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Palmieri MC, Lindermayr C, Bauwe H, Steinhauser C, Durner J. Regulation of plant glycine decarboxylase by s-nitrosylation and glutathionylation. PLANT PHYSIOLOGY 2010; 152:1514-28. [PMID: 20089767 PMCID: PMC2832280 DOI: 10.1104/pp.109.152579] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Accepted: 01/18/2010] [Indexed: 05/18/2023]
Abstract
Mitochondria play an essential role in nitric oxide (NO) signal transduction in plants. Using the biotin-switch method in conjunction with nano-liquid chromatography and mass spectrometry, we identified 11 candidate proteins that were S-nitrosylated and/or glutathionylated in mitochondria of Arabidopsis (Arabidopsis thaliana) leaves. These included glycine decarboxylase complex (GDC), a key enzyme of the photorespiratory C(2) cycle in C3 plants. GDC activity was inhibited by S-nitrosoglutathione due to S-nitrosylation/S-glutathionylation of several cysteine residues. Gas-exchange measurements demonstrated that the bacterial elicitor harpin, a strong inducer of reactive oxygen species and NO, inhibits GDC activity. Furthermore, an inhibitor of GDC, aminoacetonitrile, was able to mimic mitochondrial depolarization, hydrogen peroxide production, and cell death in response to stress or harpin treatment of cultured Arabidopsis cells. These findings indicate that the mitochondrial photorespiratory system is involved in the regulation of NO signal transduction in Arabidopsis.
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1183
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Eisenstadt D, Barkan E, Luz B, Kaplan A. Enrichment of oxygen heavy isotopes during photosynthesis in phytoplankton. PHOTOSYNTHESIS RESEARCH 2010; 103:97-103. [PMID: 20054712 DOI: 10.1007/s11120-009-9518-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2009] [Accepted: 12/16/2009] [Indexed: 05/28/2023]
Abstract
Some of the oxygen produced during oxygenic photosynthesis is consumed but little is known about the extent of the processes involved. We measured the (17)O/(16)O and (18)O/(16)O ratios in O(2) produced by certain marine and freshwater phytoplankton representing important groups of primary producers. When the cells were performing photosynthesis under very low dissolved oxygen concentrations (< 3 μM), we observed significant enrichment in both (18)O and (17)O with respect to the substrate water. The difference in δ(18)O between O(2) and water was about 4.5, 3, 5.5, and 7‱ in the diatom Phaeodactylum tricornutum, Nannochloropsis sp. (Eustigmatophyceae), the coccolithophore Emiliania huxleyi and the green alga Chlamydomonas reinhardtii, respectively. The difference in δ(17)O was about 0.52 that of δ(18)O. As explained, the observed enrichments most probably stem from considerable oxygen consumption during photosynthesis even when major O(2)-consuming reactions such as photorespiration were minimized. These enrichments increased linearly with rising O(2) levels but with different δ(17)O/δ(18)O slopes for the various organisms, suggesting engagements of different O(2)-consuming reactions with rising O(2) levels. Consumption of O(2) may be important for energy dissipation during photosynthesis. The isotope enrichment observed here, not accounted for in earlier assessments, closes an important gap in our understanding of the difference between the isotopic compositions of atmospheric oxygen and that of seawater, i.e., the Dole effect.
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Affiliation(s)
- Doron Eisenstadt
- Department of Plant and Environmental Sciences, Hebrew University of Jerusalem, Israel
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1184
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Chapter 24 Antioxidants and Photo-oxidative Stress Responses in Plants and Algae. THE CHLOROPLAST 2010. [DOI: 10.1007/978-90-481-8531-3_24] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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1185
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Athanasiou K, Dyson BC, Webster RE, Johnson GN. Dynamic acclimation of photosynthesis increases plant fitness in changing environments. PLANT PHYSIOLOGY 2010; 152:366-73. [PMID: 19939944 PMCID: PMC2799370 DOI: 10.1104/pp.109.149351] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Accepted: 11/16/2009] [Indexed: 05/18/2023]
Abstract
Plants growing in different environments develop with different photosynthetic capacities--developmental acclimation of photosynthesis. It is also possible for fully developed leaves to change their photosynthetic capacity--dynamic acclimation. The importance of acclimation has not previously been demonstrated. Here, we show that developmental and dynamic acclimation are distinct processes. Furthermore, we demonstrate that dynamic acclimation plays an important role in increasing the fitness of plants in natural environments. Plants of Arabidopsis (Arabidopsis thaliana) were grown at low light and then transferred to high light for up to 9 d. This resulted in an increase in photosynthetic capacity of approximately 40%. A microarray analysis showed that transfer to high light resulted in a substantial but transient increase in expression of a gene, At1g61800, encoding a glucose-6-phosphate/phosphate translocator GPT2. Plants where this gene was disrupted were unable to undergo dynamic acclimation. They were, however, still able to acclimate developmentally. When grown under controlled conditions, fitness, measured as seed output and germination, was identical, regardless of GPT2 expression. Under naturally variable conditions, however, fitness was substantially reduced in plants lacking the ability to acclimate. Seed production was halved in gpt2- plants, relative to wild type, and germination of the seed produced substantially less. Dynamic acclimation of photosynthesis is thus shown to play a crucial and previously unrecognized role in determining the fitness of plants growing in changing environments.
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1186
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Lawson T, von Caemmerer S, Baroli I. Photosynthesis and Stomatal Behaviour. PROGRESS IN BOTANY 72 2010. [DOI: 10.1007/978-3-642-13145-5_11] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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1187
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Andronis EA, Roubelakis-Angelakis KA. Short-term salinity stress in tobacco plants leads to the onset of animal-like PCD hallmarks in planta in contrast to long-term stress. PLANTA 2010; 231:437-48. [PMID: 19937341 DOI: 10.1007/s00425-009-1060-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Accepted: 10/30/2009] [Indexed: 05/08/2023]
Abstract
Recent results have identified mitochondria as centers of stress-induced generation of reactive oxygen species in plants. Depolarization of plant mitochondrial membrane during stress results the release of programmed cell death (PCD)-inducing factors in the cytosol in a fashion similar to the onset of animal-like PCD. Herein, we report significant similarities of animal-like PCD and salinity stress-induced plant PCD. Short-term salinity stress (3 h) led to depolarization of the mitochondrial membrane, release of cytochrome c (CYT-c), which was visualized using a contemporary molecular technique, activation of caspase-3 type proteases and the onset of PCD in wild type tobacco plants, Nicotiana tabacum cv. Petit Havana. However, PCD was not manifested during long-term salinity stress (24 h). Interestingly long-term salinity stress led to necrotic-like features, which were accompanied by collapse of respiration, reduction of key components of the respiratory chain, such as CYT-c and alternative oxidase, ATP depletion and high proteolytic activity. The results suggest that salinity stress of tobacco plants in planta leads to the onset of animal-like PCD only during the early stages post-stress, while long-term stress leads to necrotic-like features.
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Affiliation(s)
- Efthimios A Andronis
- Department of Biology, University of Crete, P.O. Box 2208, 71409 Heraklion Crete, Greece.
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1188
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Chen S, Yin C, Qiang S, Zhou F, Dai X. Chloroplastic oxidative burst induced by tenuazonic acid, a natural photosynthesis inhibitor, triggers cell necrosis in Eupatorium adenophorum Spreng. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1797:391-405. [PMID: 20026008 DOI: 10.1016/j.bbabio.2009.12.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Revised: 12/08/2009] [Accepted: 12/14/2009] [Indexed: 01/15/2023]
Abstract
Tenuazonic acid (TeA), a nonhost-specific phytotoxin produced by Alternaria alternata, was determined to be a novel natural photosynthesis inhibitor owning several action sites in chloroplasts. To further elucidate the mode of its action, studies were conducted to assess the production and involvement of reactive oxygen species (ROS) in the toxic activity of TeA. A series of experiments indicated that TeA treatment can induce chloroplast-derived ROS generation including not only (1)O(2) but also superoxide radical, H(2)O(2) and hydroxyl radicals in Eupatorium adenophorum mesophyll cells, resulting from electron leakage and charge recombination in PSII as well as thylakoid overenergization due to inhibition of the PSII electron transport beyond Q(A) and the reduction of end acceptors on the PSI acceptor side and chloroplast ATPase activity. The initial production of TeA-induced ROS was restricted to chloroplasts and accompanied with a certain degree of chloroplast damage. Subsequently, abundant ROS were quickly dispersed throughout whole cell and cellular compartments, causing a series of irreversible cellular harm such as chlorophyll breakdown, lipid peroxidation, plasma membrane rupture, chromatin condensation, DNA cleavage, and organelle disintegration, and finally resulting in rapid cell destruction and leaf necrosis. These results show that TeA causing cell necrosis of host-plants is a result of direct oxidative damage from chloroplast-mediated ROS eruption.
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Affiliation(s)
- Shiguo Chen
- Weed Research Laboratory, Nanjing Agricultural University, Nanjing 210095, China
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1189
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Kato Y, Miura E, Ido K, Ifuku K, Sakamoto W. The variegated mutants lacking chloroplastic FtsHs are defective in D1 degradation and accumulate reactive oxygen species. PLANT PHYSIOLOGY 2009; 151:1790-801. [PMID: 19767385 PMCID: PMC2785964 DOI: 10.1104/pp.109.146589] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2009] [Accepted: 09/14/2009] [Indexed: 05/18/2023]
Abstract
In the photosynthetic apparatus, a major target of photodamage is the D1 reaction center protein of photosystem II (PSII). Photosynthetic organisms have developed a PSII repair cycle in which photodamaged D1 is selectively degraded. A thylakoid membrane-bound metalloprotease, FtsH, was shown to play a critical role in this process. Here, the effect of FtsHs in D1 degradation was investigated in Arabidopsis (Arabidopsis thaliana) mutants lacking FtsH2 (yellow variegated2 [var2]) or FtsH5 (var1). Because these mutants are characterized by variegated leaves that sometimes complicate biochemical studies, we employed another mutation, fu-gaeri1 (fug1), that suppresses leaf variegation in var1 and var2 to examine D1 degradation. Two-dimensional blue native PAGE showed that var2 has less PSII supercomplex and more PSII intermediate lacking CP43, termed RC47, than the wild type under normal growth light. Moreover, our histochemical and quantitative analyses revealed that chloroplasts in var2 accumulate significant levels of reactive oxygen species, such as superoxide radical and hydrogen peroxide. These results indicate that the lack of FtsH2 leads to impaired D1 degradation at the step of RC47 formation in PSII repair and to photooxidative stress even under nonphotoinhibitory conditions. Our in vivo D1 degradation assays, carried out by nonvariegated var2 fug1 and var1 fug1 leaves, demonstrated that D1 degradation was impaired in different light conditions. Taken together, our results suggest the important role of chloroplastic FtsHs, which was not precisely examined in vivo. Attenuated D1 degradation in the nonvariegated mutants also suggests that leaf variegation seems to be independent of the PSII repair.
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1190
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Katiyar A, Lenka S, Lakshmi K, Chinnusamy V, Bansal K. In silico characterization and homology modeling of thylakoid-bound ascorbate peroxidase from a drought tolerant wheat cultivar. GENOMICS, PROTEOMICS & BIOINFORMATICS 2009; 7:185-93. [PMID: 20172491 PMCID: PMC5054410 DOI: 10.1016/s1672-0229(08)60048-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ascorbate peroxidase, a haem protein (EC 1.11.1.11), efficiently scavenges hydrogen peroxide (H(2)O(2)) in cytosol and chloroplasts of plants. In this study, a full-length coding sequence of thylakoid-bound ascorbate peroxidase cDNA (TatAPX) was cloned from a drought tolerant wheat cultivar C306. Homology modeling of the TatAPX protein was performed by using the template crystal structure of chloroplastic ascorbate peroxidase from tobacco plant (PDB: 1IYN). The model structure was further refined by molecular mechanics and dynamic methods using various tools such as PROCHECK, ProSA and Verify3D. The predicted model was then tested for docking with H(2)O(2), the substrate for TatAPX enzyme. The results revealed that Arg233 and Glu255 in the predicted active site of the enzyme are two important amino acid residues responsible for strong hydrogen bonding affinity with H(2)O(2), which might play an important role in scavenging of H(2)O(2) from the plant system.
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Affiliation(s)
- A. Katiyar
- National Research Centre on Plant Biotechnology, Indian Agricultural Research Institute, New Delhi 110012, India
| | - S.K. Lenka
- National Research Centre on Plant Biotechnology, Indian Agricultural Research Institute, New Delhi 110012, India
| | - K. Lakshmi
- National Research Centre on Plant Biotechnology, Indian Agricultural Research Institute, New Delhi 110012, India
| | - V. Chinnusamy
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA
| | - K.C. Bansal
- National Research Centre on Plant Biotechnology, Indian Agricultural Research Institute, New Delhi 110012, India
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1191
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Smith CA, Melino VJ, Sweetman C, Soole KL. Manipulation of alternative oxidase can influence salt tolerance in Arabidopsis thaliana. PHYSIOLOGIA PLANTARUM 2009; 137:459-72. [PMID: 19941623 DOI: 10.1111/j.1399-3054.2009.01305.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The growth and development of plants can be limited by environmental stresses such as salinity. It has been suggested that the non-phosphorylating alternative respiratory pathway in plants, mediated by the NAD(P)H dehydrogenase [NAD(P)H DH] and alternative oxidase (AOX), is important during environmental stresses. The involvement of this alternative pathway in a stress response may be linked to its capacity to uncouple carbon metabolism from adenylate control and/or the minimization of the formation of destructive reactive oxygen species (ROS). Salinity stress is a widespread, adverse environmental stress, which leads to an ionic imbalance, hyperosmotic stress and oxidative stress, the latter being the result of ROS formation. In this study, we show that salinity stress of Arabidopsis thaliana plants resulted in the formation of ROS, increased levels of Na+ in both the shoot and the root and an increase in transcription of Ataox1a, Atndb2 and Atndb4 genes, indicating the formation of an abridged non-phosphorylating electron transport chain in response to salinity stress. Furthermore, plants constitutively over-expressing Ataox1a, with increased AOX capacity, showed lower ROS formation, 30-40% improved growth rates and lower shoot Na+ content compared with controls, when grown under salinity stress conditions. Thus, more active AOX in roots and shoots can improve the salt tolerance of Arabidopsis as defined by its ability to grow more effectively in the presence of NaCl, and maintain lower shoot Na+ content. AOX does have an important role in stress adaptation in plants, and these results provide some validation of the hypothesis that AOX can play a critical role in cell re-programming under salinity stress.
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Affiliation(s)
- Chevaun Anne Smith
- School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide 5001, South Australia, Australia
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1192
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Janknegt PJ, de Graaff CM, van de Poll WH, Visser RJW, Helbling EW, Buma AGJ. Antioxidative Responses of Two Marine Microalgae During Acclimation to Static and Fluctuating Natural UV Radiation. Photochem Photobiol 2009; 85:1336-45. [DOI: 10.1111/j.1751-1097.2009.00603.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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1193
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Reddy RA, Kumar B, Reddy PS, Mishra RN, Mahanty S, Kaul T, Nair S, Sopory SK, Reddy MK. Molecular cloning and characterization of genes encoding Pennisetum glaucum ascorbate peroxidase and heat-shock factor: interlinking oxidative and heat-stress responses. JOURNAL OF PLANT PHYSIOLOGY 2009; 166:1646-59. [PMID: 19450902 DOI: 10.1016/j.jplph.2009.04.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 04/02/2009] [Accepted: 04/02/2009] [Indexed: 05/20/2023]
Abstract
The recent genetic and biochemical studies reveal a considerable overlap among cellular processes in response to heat and oxidative stress stimuli in plants suggesting an intimate relationship between the heat-shock response and oxidative stress responses. Pennisetum glaucum (Pg) seedlings were exposed to heat stress (42 degrees C for 0.5, 1.0 and 24h) and a mixture of RNA from all the heat stressed seedlings was used to prepare cDNA. Full-length cDNA clones encoding for cytoplasmic ascorbate peroxidase 1 (PgAPX1) and heat-shock factor (PgHSF) were isolated by screening heat stress-specific cDNA library using corresponding EST sequences as radioactive probes. These full-length cDNAs were expressed in E. coli and their recombinant proteins were purified to near homogeneity. The recombinant PgAPX1 preferred ascorbate but did not accept guaiacol as a reducing substrate. Over-expression of PgAPX1 protects E. coli cells against methyl viologen-induced oxidative stress. Sequence analysis of PgAPX1 promoter identified a number of putative stress regulatory cis-elements including a heat-shock element (HSE). Heat-shock transcription factors (HSFs) play a central role in mediating these overlapping cellular processes. Gel shift analysis and competition with specific and non-specific unlabeled DNA probes showed a specific interaction between HSE of PgAPX1 and the PgHSF protein. Expression analysis of PgHSF in Pennisetum showed maximum increase in transcript level in response to heat stress within 30 min of exposure and slowed down at subsequent time points of heat stress, indicating a typical characteristic of HSF in terms of early responsiveness. Expression of PgAPX1 significantly increased under heat-stress condition; however, the maximum expression observed at 24h of heat stress. In gel activity of PgAPX1 in Pennisetum plants also showed an increase in response to heat stress (42 degrees C) being maximum at 24h and these trends are in conformity with the expression pattern of PgAPX1. Expression patterns and interactive specificity of HSF with HSE (PgAPX1) suggest a probable vital interlink in heat and oxidative stress signaling pathways that plays a significant role in comprehending the underlying mechanisms in plant abiotic stress tolerance.
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Affiliation(s)
- Ramesha A Reddy
- International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi 110 067, India
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1194
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Marchive C, Yehudai-Resheff S, Germain A, Fei Z, Jiang X, Judkins J, Wu H, Fernie AR, Fait A, Stern DB. Abnormal physiological and molecular mutant phenotypes link chloroplast polynucleotide phosphorylase to the phosphorus deprivation response in Arabidopsis. PLANT PHYSIOLOGY 2009; 151:905-24. [PMID: 19710229 PMCID: PMC2754633 DOI: 10.1104/pp.109.145144] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Accepted: 08/19/2009] [Indexed: 05/18/2023]
Abstract
A prominent enzyme in organellar RNA metabolism is the exoribonuclease polynucleotide phosphorylase (PNPase), whose reversible activity is governed by the nucleotide diphosphate-inorganic phosphate ratio. In Chlamydomonas reinhardtii, PNPase regulates chloroplast transcript accumulation in response to phosphorus (P) starvation, and PNPase expression is repressed by the response regulator PSR1 (for PHOSPHORUS STARVATION RESPONSE1) under these conditions. Here, we investigated the role of PNPase in the Arabidopsis (Arabidopsis thaliana) P deprivation response by comparing wild-type and pnp mutant plants with respect to their morphology, metabolite profiles, and transcriptomes. We found that P-deprived pnp mutants develop aborted clusters of lateral roots, which are characterized by decreased auxin responsiveness and cell division, and exhibit cell death at the root tips. Electron microscopy revealed that the collapse of root organelles is enhanced in the pnp mutant under P deprivation and occurred with low frequency under P-replete conditions. Global analyses of metabolites and transcripts were carried out to understand the molecular bases of these altered P deprivation responses. We found that the pnp mutant expresses some elements of the deprivation response even when grown on a full nutrient medium, including altered transcript accumulation, although its total and inorganic P contents are not reduced. The pnp mutation also confers P status-independent responses, including but not limited to stress responses. Taken together, our data support the hypothesis that the activity of the chloroplast PNPase is involved in plant acclimation to P availability and that it may help maintain an appropriate balance of P metabolites even under normal growth conditions.
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Affiliation(s)
- Chloe Marchive
- Boyce Thompson Institute for Plant Research, Ithaca, New York 14853, USA
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1195
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Segovia M, Berges JA. INHIBITION OF CASPASE-LIKE ACTIVITIES PREVENTS THE APPEARANCE OF REACTIVE OXYGEN SPECIES AND DARK-INDUCED APOPTOSIS IN THE UNICELLULAR CHLOROPHYTE DUNALIELLA TERTIOLECTA(1). JOURNAL OF PHYCOLOGY 2009; 45:1116-1126. [PMID: 27032357 DOI: 10.1111/j.1529-8817.2009.00733.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
When the chlorophyte alga Dunaliella tertiolecta Butcher is placed in darkness, a form of programmed cell death with many similarities to apoptosis is induced, including the induction of caspase-like proteases. Many uncertainties about the regulation and mediators that participate in the process remain. To examine the relationship between caspase-like activities and different apoptotic events (i.e., phosphatidylserine [PS] translocation), increases in membrane permeability and numbers of dead cells revealed by SYTOX-green staining, and the generation of reactive oxygen species (ROS), we used the broad-range caspase inhibitor Boc-D-FMK to block the activity of the whole class of caspase-like proteins simultaneously. In the presence of the inhibitor, ROS were not produced, and cells did not die. Loss of membrane asymmetry, indicated by external labeling of PS by annexin V, was apparent at midstages of light deprivation, although it did not conform to the typical pattern for PS exposure observed in metazoans or vascular plants, which occurs at early stages of the apoptotic event. Thus, we have evidence for a link between ROS and cell death involving caspase-like enzymes in an alga. The fact that caspase-like inhibitors prevent not only cell death, but also ROS and loss of cell membrane integrity and asymmetry, suggests that caspase-like proteases might have regulatory roles early in cell death, in addition to dismantling functions.
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Affiliation(s)
- María Segovia
- Department of Ecology, Faculty of Sciences, University of Málaga, Bulevar Louis Pasteur s/n, 29071-Málaga, SpainDepartment of Biological Sciences, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wisconsin 53201, USA
| | - John A Berges
- Department of Ecology, Faculty of Sciences, University of Málaga, Bulevar Louis Pasteur s/n, 29071-Málaga, SpainDepartment of Biological Sciences, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wisconsin 53201, USA
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1196
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Mano J, Miyatake F, Hiraoka E, Tamoi M. Evaluation of the toxicity of stress-related aldehydes to photosynthesis in chloroplasts. PLANTA 2009; 230:639-48. [PMID: 19578873 DOI: 10.1007/s00425-009-0964-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Accepted: 05/18/2009] [Indexed: 05/03/2023]
Abstract
Aldehydes produced under various environmental stresses can cause cellular injury in plants, but their toxicology in photosynthesis has been scarcely investigated. We here evaluated their effects on photosynthetic reactions in chloroplasts isolated from Spinacia oleracea L. leaves. Aldehydes that are known to stem from lipid peroxides inactivated the CO(2) photoreduction to various extents, while their corresponding alcohols and carboxylic acids did not affect photosynthesis. alpha,beta-Unsaturated aldehydes (2-alkenals) showed greater inactivation than the saturated aliphatic aldehydes. The oxygenated short aldehydes malondialdehyde, methylglyoxal, glycolaldehyde and glyceraldehyde showed only weak toxicity to photosynthesis. Among tested 2-alkenals, 2-propenal (acrolein) was the most toxic, and then followed 4-hydroxy-(E)-2-nonenal and (E)-2-hexenal. While the CO(2)-photoreduction was inactivated, envelope intactness and photosynthetic electron transport activity (H(2)O --> ferredoxin) were only slightly affected. In the acrolein-treated chloroplasts, the Calvin cycle enzymes phosphoribulokinase, glyceraldehyde-3-phosphate dehydrogenase, fructose-1,6-bisphophatase, sedoheptulose-1,7-bisphosphatase, aldolase, and Rubisco were irreversibly inactivated. Acrolein treatment caused a rapid drop of the glutathione pool, prior to the inactivation of photosynthesis. GSH exogenously added to chloroplasts suppressed the acrolein-induced inactivation of photosynthesis, but ascorbic acid did not show such a protective effect. Thus, lipid peroxide-derived 2-alkenals can inhibit photosynthesis by depleting GSH in chloroplasts and then inactivating multiple enzymes in the Calvin cycle.
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Affiliation(s)
- Jun'ichi Mano
- Science Research Center, Yamaguchi University, Yamaguchi 753-8515, Japan.
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1197
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Huseynova IM, Suleymanov SY, Rustamova SM, Aliyev JA. Drought-induced changes in photosynthetic membranes of two wheat (Triticum aestivum L.) cultivars. BIOCHEMISTRY (MOSCOW) 2009; 74:903-9. [DOI: 10.1134/s0006297909080124] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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1198
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Manning VA, Chu AL, Steeves JE, Wolpert TJ, Ciuffetti LM. A host-selective toxin of Pyrenophora tritici-repentis, Ptr ToxA, induces photosystem changes and reactive oxygen species accumulation in sensitive wheat. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2009; 22:665-76. [PMID: 19445591 DOI: 10.1094/mpmi-22-6-0665] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Ptr ToxA (ToxA) is a proteinaceous necrotizing host-selective toxin produced by Pyrenophora tritici-repentis, a fungal pathogen of wheat (Triticum aestivum). In this study, we have found that treatment of ToxA-sensitive wheat leaves with ToxA leads to a light-dependent accumulation of reactive oxygen species (ROS) that correlates with the onset of necrosis. Furthermore, the accumulation of ROS and necrosis could be inhibited by the antioxidant N-acetyl cysteine, providing further evidence that ROS production is required for necrosis. Microscopic evaluation of ToxA-treated whole-leaf tissue indicated that ROS accumulation occurs in the chloroplasts. Analysis of total protein extracts from ToxA-treated leaves showed a light-dependent reduction of the chloroplast protein RuBisCo. In addition, Blue native-gel electrophoresis followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis revealed that ToxA induces changes in photosystem I (PSI) and photosystem II (PSII) in the absence of light, and therefore, the absence of ROS. When ToxA-treated leaves were exposed to light, all proteins in both PSI and PSII were extremely reduced. We propose that ToxA induces alterations in PSI and PSII affecting photosynthetic electron transport, which subsequently leads to ROS accumulation and cell death when plants are exposed to light.
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Affiliation(s)
- Viola A Manning
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331, USA
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1199
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Li Z, Ahn TK, Avenson TJ, Ballottari M, Cruz JA, Kramer DM, Bassi R, Fleming GR, Keasling JD, Niyogi KK. Lutein accumulation in the absence of zeaxanthin restores nonphotochemical quenching in the Arabidopsis thaliana npq1 mutant. THE PLANT CELL 2009; 21:1798-812. [PMID: 19549928 PMCID: PMC2714924 DOI: 10.1105/tpc.109.066571] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 05/06/2009] [Accepted: 06/04/2009] [Indexed: 05/19/2023]
Abstract
Plants protect themselves from excess absorbed light energy through thermal dissipation, which is measured as nonphotochemical quenching of chlorophyll fluorescence (NPQ). The major component of NPQ, qE, is induced by high transthylakoid DeltapH in excess light and depends on the xanthophyll cycle, in which violaxanthin and antheraxanthin are deepoxidized to form zeaxanthin. To investigate the xanthophyll dependence of qE, we identified suppressor of zeaxanthin-less1 (szl1) as a suppressor of the Arabidopsis thaliana npq1 mutant, which lacks zeaxanthin. szl1 npq1 plants have a partially restored qE but lack zeaxanthin and have low levels of violaxanthin, antheraxanthin, and neoxanthin. However, they accumulate more lutein and alpha-carotene than the wild type. szl1 contains a point mutation in the lycopene beta-cyclase (LCYB) gene. Based on the pigment analysis, LCYB appears to be the major lycopene beta-cyclase and is not involved in neoxanthin synthesis. The Lhcb4 (CP29) and Lhcb5 (CP26) protein levels are reduced by 50% in szl1 npq1 relative to the wild type, whereas other Lhcb proteins are present at wild-type levels. Analysis of carotenoid radical cation formation and leaf absorbance changes strongly suggest that the higher amount of lutein substitutes for zeaxanthin in qE, implying a direct role in qE, as well as a mechanism that is weakly sensitive to carotenoid structural properties.
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Affiliation(s)
- Zhirong Li
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720-3102, USA
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Ni FT, Chu LY, Shao HB, Liu ZH. Gene expression and regulation of higher plants under soil water stress. Curr Genomics 2009; 10:269-80. [PMID: 19949548 PMCID: PMC2709938 DOI: 10.2174/138920209788488535] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Revised: 04/25/2009] [Accepted: 04/27/2009] [Indexed: 01/08/2023] Open
Abstract
Higher plants not only provide human beings renewable food, building materials and energy, but also play the most important role in keeping a stable environment on earth. Plants differ from animals in many aspects, but the important is that plants are more easily influenced by environment than animals. Plants have a series of fine mechanisms for responding to environmental changes, which has been established during their long-period evolution and artificial domestication. The machinery related to molecular biology is the most important basis. The elucidation of it will extremely and purposefully promote the sustainable utilization of plant resources and make the best use of its current potential under different scales. This molecular mechanism at least includes drought signal recognition (input), signal transduction (many cascade biochemical reactions are involved in this process), signal output, signal responses and phenotype realization, which is a multi-dimension network system and contains many levels of gene expression and regulation. We will focus on the physiological and molecular adaptive machinery of plants under soil water stress and draw a possible blueprint for it. Meanwhile, the issues and perspectives are also discussed. We conclude that biological measures is the basic solution to solving various types of issues in relation to sustainable development and the plant measures is the eventual way.
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Affiliation(s)
- Fu-Tai Ni
- 1College of Life Sciences, Jilin Normal University, Siping 136000, China
| | - Li-Ye Chu
- Institute of Life Sciences, Qingdao University of Science & Technology, Qingdao 266042, China
| | - Hong-Bo Shao
- 2State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences, Yangling 712100, China
- 3Shandong Key Laboratory of Eco-environmental Science for Yellow River Delta, Binzhou University, Binzhou 256603, China
- Institute of Life Sciences, Qingdao University of Science & Technology, Qingdao 266042, China
| | - Zeng-Hui Liu
- Institute of Life Sciences, Qingdao University of Science & Technology, Qingdao 266042, China
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